Ivan Seeking said:
I remember that as well, but 2/113 is not 1/100.

Of course it is! Catastrophic failures can only occur in integer values, so those two rates are in the same range of significant digits. Ie, you
cannot extrapolate that 2/113 to be 4/226, 8/452, etc. "Real" odds can only be calculated on sample sizes large enough to eliminate the small, random fluctuations. The Challenger blew up on the 25th launch, the Columbia on the 113th.
Besides - I did say "ballpark" to avoid arguing this issue. Whether its 1/100 or 1/50, that's still the same ballpark in my book.
The exact same(opposite, really) problem exists with cacluating airline travel risks: In a most years (recently, anyway), there are no deaths at all from domestic, commercial airline crashes. So the calculated fatality rate would be 0/100,000 departures. Obviously, a meaningless number.
Along the same lines, while no one died on a spaceflight any of the first three space programs (mercury, gemini, apollo). That 0/~20 perfect failure rate
cannot be taken to mean that those programs were safer. They were not. In fact, engineers were almost
shocked that no one died in those programs. Those astronauts strapped themselves into rockets thinking they had somewhere on the order of a 10-20% chance of dying that day.